Indicating instrument for aircraft



2 `Sheets-Sheet l INVENTOR.

Harvey Day/e H. DOYLE INDIZCATING INSTRUMENT FOR AIRCRAFT Filed May 25,1935.

pr 25,A N339.

WMI!" IN 30o 6o x April 25, 2939. H DOYL 2,156,012

INDICATING INSTRUMENT FOR AIRCRAFT Filed May 25, 1935 2 Sheets-Sheet 2Patented Apr. 25, 1939 UNITED STATES PATENT OFFICE Application May z5,1935, serial No. 23,504

4 Claims.

The present invention relates to indicating instruments, and moreparticularly to indicating instruments for use on aircraft equipped withretractible landing gear.

One of the objects of the invention is to provide novel indicating meansfor use in aircraft having retractible landing gear whereby a warningwill be given to the pilot of the aircraft as to the position of theretractible landing gear in order that said gear is not inadvertentlyleft in a wrong position.

Another object is to provide novel means whereby such warning is givenby a visual signal on the instrument board to which the pilots attentionis constantly directed, said novel means thus being effective to keepthe pilot's attention to the board, rather than detract it therefrom.

Another object is to provide an air speed indicator having novel meanswhereby the pilots attention is fixed to that range of speeds on thescale of the air speed indicator. which is most important under theparticular circumstances of the flight as, for example, in take oi andlanding.

Still another object is to provide a novel signal device for warning apilot whether the retractible landing gear of his aircraft is in an upor ldown position, and particularly an electrically operated indicatingdevice which is not energized and actuated to indicate a down positionof the landing gear until the latter is in its fully extended downposition, thereby insuring the pilot that he may safely land hisaircraft.

A still further object of the invention is to provide in an aircrafthaving retractible landing gear, a novel combination including contactmeans controlled by the landing gear. an air speed indicator, a landinggear position indicator, and a dial-obscuring shield, both of the latterbeing incorporated in the casing of the air speed indicator and actuatedupon operation of said contact means.

The above and other objects and advantages of the invention will appearmore fully hereinafter from a consideration of the detailed descriptionwhich follows, taken together with the accompanying drawing wherein oneembodiment of the invention is illustrated.' It is to be expresslyunderstood, however, that the drawings are for l the purpose ofillustration and description only and are not intended as a definitionof the limits of the invention. reference beinghad for this purpose tothe appended claims.

In the drawings, wherein like reference characters refer to like partsthroughout the several views,

(ci. r11-su) Fig. 1 is a front view of an air speed indicator embodyingthe invention, showing all signals as same might appear to a pilot;

Fig. 2 is a vertical partly sectional view of the air speed indicator ofFig. 1, showing only that 5 tpart of the structure which embodies theinven- Fig. 3 shows the manner in which the landing gear positionindicator is mounted in the casing of the air speed indicator, otherdetails of the air speed indicator mechanism being removed for the sakeof clearness;

Fig. 4 taken on line 4 4 of Fig. 2 is a front view of the actuatingsolenoid with guide assembly attached, showing its position in the airspeed indicator casing, element 9 being omitted for clarity;

Fig. 5 is a partial front view of an aircraft having a retractiblelanding gear, with parts of its Wings removed in order to show thecontrolling electric contact means; and

Figs. 6 to 10, inclusive, illustrate another embodiment of the inventionand are views respectively similar to the views shown in Figs. 1 to 5,inclusive. l 25 Referring first to Figs. 1 to 5 of the drawings, whichillustrate one embodiment of the invention, the novel indicatingapparatus embodying the invention comprises an air speed indicator 6having a dial 'i provided with a scale l, a landing gear positionindicator 9, a scale-obscuring shield I0, said indicator 9 and shieldill being incorporated in the casing il of the air speed indicator, andelectric contact means carried by the aircraft (Fig. 5) and includingcontacts i2, contact disk i3, a solenoid I4 and a source i5, saidcontact means being adapted to be actuated by the landing gear of theaircraft (Fig. 5).

Referring now more particularly to Fig. 5, the electric contact meansconsist of an electric circuit i5a including the source of electriccurrent I5, connecting leads l5b and |5c, contacts I2, and solenoid i4,said solenoid being incorporated in the casing 6 of the air speedindicator, as shown in Fig. 4. The contacts i2 are installed at somesuitable place in the aircraft, and are adapted to be closed by somepart of the retractible landing gear when same is in its retractedposition. In the present embodiment, the contacts I2 are installed inthe aircraft wing at a point where they can be closed by the contactdisk i3 which is attached to the hub of the landing wheel i8, when saidwheel is moved into its retracted position, as indicated vby' the dottedlines in Fig. 5. It is, of course, possible to install said contactmeans in various other places of the aircraft where similar cooperationthereof with the landing gear may be accomplished.

'I'he solenoid I4 is mounted in the air speed indicator casing Il ofindicator 8 (see Fig. 2), and is provided with a moving core or plungerI1 having a guide assembly I8 attached to it in any suitable manner,said guide assembly being adapted to be raised by the solenoid I4 whenthe contacts I2 are closed. 'Ihe guide assembly i8 is in the form of aU-shaped guide member I9 (see Fig. 4) having an internal channel ortract 28 on one of its legs and cooperating with a roller 2l. A rack 22is formed on the other leg oi' the U-shaped member, which rackcooperates with a pinion 23 to actuate the same when the plunger isdrawn into the solenoid I4. The pinion 28 is mounted on a sleeve 24which carries the indicating plate 8 and the semi-transparent shield I8.Said plate 8 has two indicating portions 29 and 28 having thereon theinscription up and down, respectively, as shown on Fig. 3, which areadapted to be moved alternately opposite an opening 21 of the dial 1 ofthe air speed indicator 8. Plate 9 is so mounted on the sleeve 24 thatwhen the guide assembly I8 is raised by the solenoid I4, the upindicating portion shows in the opening or window 21 and when thesolenoid is de-energized, the down portion shows through the window 21.'I'he semitransparent shield III is mounted on the sleeve 24 in front ofthe dial 1 and rotates together with the indicator 9. The shield I is somounted that when indicator 9 is in its up position, said shield coversthe low-speed portion of the scale 8 on the dial 1; and when indicator 9is in its down position, said shield III covers the highspeed portion ofsaid scale. 'Ihis shield may be made in a variety of forms, preferablyin the form of a sector in order not to obscure the opening 21. A shaft28 extends through the sleeve 24 and carries a pointer 29 which issecured to that portion of the shaft which protrudes out of said sleeve24, said shaft 28 being rotatable independently of the sleeve 24 by theair speed mechanism (not shown).

Air speed is usually very carefully checked by the pilot during climbandafter take on', in cruising, and during the glide when landing.During the take off and in landing, the landing gear of the aircraft isin its extended position. In this case the contacts I2 are open wherebythe solenoid I4 is de-energized and the core I 1 of the solenoid is inits down position, and, consequently, the down portion 26 of theindicator 9 is visible in the opening 21. At the same time thehigh-speed portion of the scale 8 of the dial 1 is obscured by theshield I0. When higher speeds are attained and the landing gear isretracted, the contact disk I8 closes the contacts I2 whereby solenoidI4 is energized from the source I and the guide assembly I8 is raised,thus causing the rack 22 to actuate the gear 23 whereby the indicator 9is moved into its up position. The shield Ill is also moved andfunctions to obscure the low speed portion of the scale 8 of dial 1,which portion does not need attention at the higher speeds.

When the speed of the aircraft is reduced, as when it is desired toland, and the landing gear is extended, the contacts I2 are openedwhereby the solenoid I4 is de-energized and the indicator 9 and theshield I0 are returned to their respective down positions by gravity.

Referring now to Figs. 6 to 10, inclusive, there 2,ise,o12

is shown another embodiment of the invention, wherein the indicatingflag 9 is actuated into the down position when the solenoid I4 isenergized and returns to the up position by gravity. I'his arrangementinsures the pilot that the landing gear is in its fully extended downposition when the indicator shows "down and, hence, prevents attemptedlandings without the gear being in fully extended position. For thispurpose, the contact I3, instead of being carried on the hub of thewheel I6, is carried by a threaded member Ila which cooperates with thethreaded operating shaft lib to move the pivoted arm I3c outwardly andinwardly and, hence, to retract and extend the wheel I9 of the land- Inggear. The contacts I2 are then located in a position adjacent the drivenend of the threaded shaft i9b so that the contact I9 does not close thecontacts I2 until the threaded member Ila is in the extreme leftposition, as viewed in Fig. l0, and the wheels I6 are in the fullyextended down position, whereupon the circuit I5a is closed and solenoidI4 (see Fig. 9) becomes energized and pulls plunger I1 thereinto tooperate rack 22 and pinion 23 as shown in Figs. 7 and 9. The "downportion of the indicator 9 is then moved into its indicating position soas to be visible through the window 21. In this embodiment, the flag 9rotates clockwise upon energimtion of the solenoid I4 as in Figs. 1 to5, thereby causing the flag 9 and the shield Ill to revolve throughapproximately only 130 degrees instead of 230 degrees from one positionto another. The reason that only 130 degrees rotation is needed is dueto the fact that in this embodiment the indicator 9 indicates down whenthe solenoid is in its up or energized position, or in other words, thereverse of Figs. 3 and 4.

Also during cruising, no current is consumed from the battery I5 becausethe circuit lia is open at that time and is closed only when the pilotis going to land his craft and after he lands, he can open the circuitby a suitable hand switch (not shown).

From the foregoing it will be apparent that there are thus providednovel means whereby a visual signal is always given to the pilot of anaircraft as to the position of the retractible landing gear carried bythe aircraft and Whereby the pilots attention is fixed to the narrowedspace of the air speed indicator scale requiring special attention underthe changing conditions of speed.

Although only two embodiments of the invention have been illustrated anddescribed, other changes and modifications in the form and relativearrangement of parts, which will appear to those skilled in the art, maybe made Without departing from the scope of the invention. Reference is,therefore, to be had to the appended claims for a definition of thelimits of the invention.

What is claimed is:

l. The combination with an aircraft having retractible landing gear, ofan air speed indicator having a dial provided with a scale, asemitransparent shield for alternately obscuring the low-speed and thehigh-speed portions of said scale, and means actuated by said landinggear for operating said semi-transparent shield.

2. In an air speed indicator for aircraft having retractible landinggear, an indicator including a scale for indicating air speed over theoperating range of the instrument, means cooperating with said scale andcontrol means therefor whereby said cooperating means are actuated inaccordance with the position of the landing gear for emphasizing oneportion of said scale when the landing gear is in extended position andanother portion when the landing gear is in the retracted position.

3. In an air speed indicator for aircraft having retractible landinggear, an indicator including a scale for indicating air speed over theoperating range of the instrument, means cooperating with said scale andmeans connecting said cooperating means to said landing gear wherebysaid cooperating means are actuated in accordance with the position ofthe landing gear for emphasizing the lower range of the scale when thelanding gear is in extended position and the upper range when thelanding gear is in retracted position.

4. In an air speed indicator for aircraft having retractible landinggear, an indicator including a scale for indicating air speed over theoperating range of the instrument, means cooperating with said scale forrendering the upper range of the scale less 'visible when the landinggear is in extended position and the lower range of said scale lessvisible when the landing gear is in retracted position and meansactuating said cooperating means in accordance with the position of saidlanding gear.

HARVEY DOYLE.

